In power generating and working rotating machinery, such as wind machines and rope or cable driven and carried transport systems, relative motion between magnetic field generators and coils produces electricity, one of these groups being mounted on a rotor and the other group being mounted on a stator of the power generating machine. The magnetic field generators are typically windings, which are electromagnets supplied with a small portion of the output of the power generating machine. However, permanent magnets can instead be used to provide a magnetic field that induces electrical current in conductors when relative motion occurs between the magnets and the conductors. But permanent magnets are relatively heavy, and when used in large scale machinery, the apparatus used to hold the magnets in place can add substantially more undesirable weight, are difficult to install, are limited in the sizes of magnets they can accommodate, or are overly costly. For example, in some applications, the magnets are glued to a rotor body, the glue being applied under pressure. Additional applications use stampings over the ends of the magnets to hold them in place. Still other applications employ clamps, each clamp having an end attached to the underside of the rotor body and another end extending over the body of the magnet.
In known magnet assemblies, core plate stacks are used to support windings or magnets and shape the magnetic fields thereof. Such core plate stacks include a plurality of sheets of metal, such as metal stampings with desired profiles. The sheets are aligned and have through holes that form a bore through which preformed tie rods or bolts are inserted that hold the plate stacks together. In the known arrangements, the tie rods are attached to the end plates of their respective stacks in various ways.
An example of such known core plate stacks is disclosed in PCT application WO/97/30504, which also discloses a core plate stack production procedure. To form a core plate stack, a plurality of substantially identical sheets or plates are placed one atop another with end plates on either end of the stack. To hold the stack together, preformed tie bolts are inserted through bores formed by aligned through holes of the plates, but the tie rods are not secured to the end plates per se. Rather, the assembly of plates and tie rods is placed within a winding body that holds the stack and rods in place while the winding is installed and until the final assembly steps are performed. The final assembly steps include placing the winding, complete with core plate stack, tie rods, and winding body, into a mold and flooding the mold with a resin, allowing the resin to cure, and removing the resin-covered and -impregnated winding assembly from the mold. It should be noted that the preformed tie rods are disclosed as being steel or aluminum.
Such known core plate stacks and windings are relatively heavy due in part to the metal preformed tie rods and the extra end plates that are typically substantially thicker than the bulk of the plates in the stack. Additionally, because of the resin in which the winding and core plate stacks are embedded, it is nearly impossible to repair should anything go wrong or to swap out a part should an operating condition change. Additionally, such known core plate assemblies are not easily adapted to use with permanent magnets